With the last series of entrants fielded in 1989/1990 AAI fielded a refined model of their previous models for consideration. Firing a 5.56 Flechette round (which was believed to be more effective in creating wounds) the weapon shared many features in with its predecessors. A standard arrangement was utilized, a selector switch allowed for firing on semi-automatic or 3 round burst mode. Equipped with iron sights and the ACOG sight (which precipitated the use of this scope in the military) the weapon could be used even in low light conditions without replacing the sight. One feature unique to the AAI version is that when fired on burst mode three rounds cycle at once, allowing for the rounds to be downrange before the shooter has felt the recoil effects. One of the problems AAI feared is that a user might try and place an M-16 magazine into the weapon and attempt to fire conventional 5.56 NATO ammunition in the weapon. A malfunction would occur during such a situation, threatening to possibly damage the weapon if not the user. As such the magazine well was designed to ensure that the M-16 magazine would not fit and could not be inserted. The magazine AAI developed will only fit the flechette round and not a standard ball round. There were plans by AAI (once they had been awarded the contract) to begin production of a whole series of ACR weapons, including a carbine variant and a Squad Automatic Weapon design.